一个改进的T42L10谱模式及其在月预报中的应用

将一个改进的 T42L10月长期数值预报谱模式,与(国家气象中心引进的)原 T42L9谱模式进行了比较.该模式改进和提高了在σ面上模式初值的精度;在辐射计算中,用模式的预报水汽场和模式诊断云代替原模式(T42L9)中的气候纬向平均水汽场和云,并考虑了由于大地形作用对云的影响;采用了七层谱模式中对低纬的改进预报方法(如对水平扩散过程),以改进T42L10在低纬的月预报结果;考虑了海温及下垫面状态在月预报中随预报时效的变化.用改进的 T42L10谱模式对1992年4月、6月、7月、9月作月长期数值预报试验.试验表明,500hPa 高度月预报平均的 R 值(倾向相关系数)在中高纬和低纬地区分别为0.76和0.64;模式预报的均方根误差月平均比对应的持续性误差小.

AN IMPROVED T42L10 SPECTRAL MODEL AND ITS APPLICATION TO MONTHLY OPERATIONAL FORECAST IN 1992

An improved T42L10 spectral model in comparison with the T42L9 model fromNMC has the following advantages:(1)the accuracy of initial fields is increased on the olevel;(2)the mean zonal climatic cloud and vapour fields are taken the place of thediagnostic cloud and forecast vapour fields,giving consideration to the effect of theQinghai-Xizang Plateau on cloud model;(3)the forecasts in the lower latitude areimproved by use of some methods from the seven-level spectral model (such ashorizontal diffusion process);(4)the variations with time of SST,soil humidity,icecovering,etc.are considered.The improved T42L10 was applied to the operationalforecast in April,June,July and September of 1992.The correlation coefficients of500hPa are 0.76 and 0.64 in the high-middle latitude and lower latitude areas,respectively.The forecast errors are lower than those of the persistence forecasts in the30-day forecasts.